Prediction of optimal dimensions and arrangements of circular tubes of a fin and tube heat exchanger for an improved thermal-hydraulic performance

Abstract

In the present work, the thermal-hydraulic performance of a fin and tube compact heat exchanger (FTHE) with different spatial arrangements of tubes and variations of tube diameter is investigated numerically. The three types of spatial arrangement of the tubes, namely inline, staggered row (SR), and staggered column (SC) arrangements, and five different tube diameters starting from Dc = 6.51 mm to Dc = 10.51 mm considered with a constant increment of 1 mm, are investigated for the augmentation of the heat transfer. The entire analysis is conducted under the low inlet velocity ranging from 0.7 m/s to 1.1 m/s. The results indicate that FTHEs (flow-through heat exchangers) have better thermal-hydraulic performance when arranged in staggered column configurations compared to inline and staggered row arrangements. However, it was observed that the pressure drop increased in staggered column arrangements compared to inline and staggered row arrangements. The performance ranking method MOORA is applied to optimize the spatial arrangements of tubes. The study’s findings suggest that the performance of FTHE is better in the case of staggered column arrangements, which offer a fair agreement with performance evaluation criteria (PEC3 = Q/(Pf +Pp )). After achieving the staggered column arrangement as an optimum spatial arrangement of the tubes, the influence of tube diameter on the performance of FTHEs is investigated for this arrangement only. The findings indicate that when the tube diameter is increased, there is a corresponding increase in both the characteristics like heat transfer coefficient and the pressure drop penalty. The performance ranking method MOORA is applied to get an optimum tube diameter, which is cross-checked by the TOPSIS method. Based on PEC3 and two optimization approaches, MOORA and TOPSIS, it is revealed that a larger tube diameter leads to better overall performance of the FTHEs.